1. Technical Field
This invention relates generally to a method of cleaning a glass substrate and an apparatus for the same in which various foreign materials, e.g., glass cullets adhered to the surface of the glass substrate are effectively removed.
2. Related Art
Many thin layers of electrodes, insulators and the like are formed on a glass substrate, e.g., the one used for a liquid crystal display panel. The surface of such a glass substrate should, thus, have no foreign materials and be sufficiently clean.
Further, such a liquid crystal display panel includes a pair of sheet-like glass substrates between which a liquid crystal layer is held and in its production process a mother glass substrate is cut out to make the sheet-like glass substrates a desired size. Since this results in leaving foreign materials including mainly glass cullets on the outer surfaces of the sheet-like glass substrates, it causes inconvenience when optical films, e.g., polarizers are put thereon.
Generally, a cleaning apparatus cleans up mother glass substrate surfaces and/or liquid crystal display panel surfaces so that foreign materials adhered thereto are removed in advance. The cleaning apparatus has relatively slender strip-like squeegees. The squeegees are driven along a predetermined direction on the glass surface with the blades thereof contacting on the glass surface so that various foreign materials thereon, such as glass cullets, are physically eliminated. As disclosed in Japanese Patent Publication (Tokkaihei) 4-93816 or the like, the squeegees are driven once or repeatedly from a same direction along the scanning path on the glass surface in a conventional cleaning process.
According to such a conventional cleaning method, the blades always contact on foreign materials from the same direction so that the foreign materials on the glass surface receive removing force from one direction only. Further, the blades contact on the foreign materials only once in the cleaning cycle. As a result, the foreign materials cannot always be eliminated from the glass surface in the case of some types of a foreign materials or adhesive conditions thereof so that sufficient cleanness of the glass surface is not necessarily achieved in the conventional method or apparatus. Driving the squeegees in the prior art cleaning method may be more often repeated. The processing time in such cases, however, becomes much longer and the cleaning efficiency is not always satisfactory.